I thought my wife was just reacting to the screen door's cold temperature this afternoon when she claimed it was shocking her as she touched it.  I touched it and didn't get much of a buzz if any.

We've had rain here all day, so the ground is very wet.  I have the trailer plugged into a grounded outlet, but the extension cord is not grounded.

I measured the voltage from the trailer skin directly to the ground with a voltmeter... yup... 110 volts AC, clean.  Wonder what would happen if we were barefoot and touched the trailer... :-)

Is this normal?  Would using a grounded extension cord between outlet and trailer help?  Is there a problem with my trailer's wiring?  The wiring is pretty simple--extension cord from outlet plugs into box in side of trailer, which connects 2 outlets inside the trailer and the A/C unit.

Help is appreciated.

Mike

RAH ... A timely posting. 

Mr Truck has published my article that explains your problem and a likely cause.

(Please take this as a shameless plug for his site and my article...)

Click here >>  http://www.mrtrailer.com/hosspuller.htm

RAH ....

Another thought.  besides the obvious wiring short,  You might have a reversed connection along with the bonded neutral wire.  That would charge the trailer too.

Thanks, EVERYONE, for your replies.  This could be a very serious problem.  I'll try a proper extension cord first, then some other outlets/generator and see if that does not solve the problem.

If that doesn't do the trick, then we're off to Silver Star soon anyway.  I'll post back what we find.  My hunch is that there are wiring issues from the barn, anyway.  We rent a house, barn, and 10 acres... I'm finding that the whole house and other buildings here on the grounds have not been wired the way they should have been.

Thank you,

Mike

Okay... so I missed going to my endurance horse race this weekend due to some computer issues at work that needed my attention.  Air Force... Service Before Self, HUA!?!?

With all the free time I had after arriving home this evening, I checked into the electrical issue a bit further...

On GENERATOR power, grounded extension cord or not, I get 20 volts from the trailer to the ground.

On A/C power from the barn, I get a full 110 volts from the trailer to the ground WITH a grounded extension cord.

So it looks like the problem is with the barn's electrical wiring and likely lack of a proper ground.  I'll be talking to an electrician...

One question remains: is the 20 volts shown on generator power significant?

Thank you,

Mike

That brought MANY chuckles.  After having to cancel on a race I'd hoped to be heading to today due to work commitments, thanks for making my day.

The barn's wiring might not be the problem.  Your trailer's short may not be leaking enough power to trip the breaker.  It'll take MORE than 15-20 amps to trip the breaker with a grounded ext cord.  That kind of power would light your wife's eyes with more than love for you.  The tingle you feel is only several milliamps.  Not even a tenth of an amp.

If your generator is self contained, and you're still measuring 20 volts to ground (which ground?) it's only because of the resistance of the trailer tires.  You have a wiring problem.  Your wife has you. Both are deadly serious problems.  LOL

Hosspuller,

The voltage was measured the same way when the trailer was run from the barn and when the trailer was run from the generator.  Tires should be out of the loop here because I measured voltage from the metal trailer door through the voltmeter directly to the ground (dirt, earth, etc.)  Voltmeter probes were touching the trailer and dirt directly.  If tires were in the loop for the genset, then they'd still have been in the loop for the A/C from the barn.

My explanation ^^^^^ makes sense to me... so either I didn't explain adequately in my first post OR I'm seriously not understanding what's going on...  :-)

I'll bet you a dollar to a Doughnut... that if you measure from trailer to the frame of the genset you'll get 110 volts.  The genset is only sitting on the ground.  A driven ground rod for the genset will truly ground the genset, completing the low resistance circuit.  In this case, it's the high resistance between the genset and the ground that is dropping the 110 volts to 20 volts.

It is not the barn wiring ... it is your trailer.

Hosspuller, your is a plausible explanation.  I'll try to research it further tomorrow.

Retento... no screws anywhere.  This is something that may have been preexisting from before the insulation project.  I did replace the electrical box awhile back because the unit that came from the factory was messed up--should never have been put on the trailer to begin with, as the connector prongs were broken and moved into the box whenever a cord was connected, resulting in no connection.  I'll pull the box tomorrow and have a look.

Thanks,

Mike

Another wager... The cord you're using has a faulty ground or the trailer's inlet has a faulty ground. (The inlet's ground prong should be connected to the frame of the trailer)

If both of these parts had a working ground, either the genset or barn outlet should have grounded the current you measured.

Okay, I got a few minutes to take a closer look at the trailer today. BIG PROBLEM!  When I rewired the inlet, I copied how it was done from the factory without realizing that there was never a ground done!  More than likely, put it on my list of "things to check with the dealer" and got busy/forgot.

There are some pictures at the links below.  What do I need to do to fix the problem?

You will see that the green wires (I assume they're ground) run from the connector at the bottom of the plug (flipped upside down in the picture) to the air conditioner wiring (goes into the box, then up the trailer wall).  There is no connection from the green screw on the inlet to anything.  Does it need to be connected to the plug/receptacle where the other green wires are connected?  Does it connect somehow to the trailer skin?

Help please... thanks to all for their thoughts.  I don't know how this slipped past me when I rewired the trailer box upon installing the new black connector, but can assure you the connection was never done from the factory, either.

http://www.horsetrailerworld.com/forum/photos/show-album.asp?albumid=77&currentpos=7

http://www.horsetrailerworld.com/forum/photos/show-album.asp?albumid=77&currentpos=8

Thank you,
Mike

Do you by chance have a part number for such a device?  Where can I get one?

Thank you,

Mike

Hello RAH ....

You've found part of your problem.  The ground wire is not connected.  While anything plugged into your GFCI is protected, the whole trailer is left unprotected. (as you found out)

For a start.  Connect the green wires to the grounding terminal of the inlet.  Run another green wire to the frame of the trailer.  All the green wires (ground) should be only connected to other green wires and to the trailer frame.

Can't tell from your photo's... the white wire should be connected to the white terminal of the inlet.  These are your neutral wires.  No where should they interconnect to the green wire.  (As my article stated, this is proper for a house service entrance but your trailer isn't a house electrically)

This could be the other part of your problem if the inlet connections are interchanged.  White wires to white terminal... Black wires to brass colored terminal.

A way to test this is, with all the internal trailer wires removed from the inlet + inlet plugged to extension cord:

1)measure between the white wire and ground... should be zero volts

2) measure between black wire and ground...should be 110 volts.

Hosspuller,

Thank you for your reply.  In the picture, it looks like the black wires are connected to where you say the white (yellow, actually) wires should be connected (I assume the silver screw on righthand side is what you're terming as the "white terminal of the inlet.")  As you can see, the white (yellow) wires are connected to a screw that is coated with rust.

I assume the rusted terminal is the brass terminal is the one with all the rust on it.  The black wires appear to be connected by stainless steel hardware.  Switch them to the place where the white/yellow wires are now?

Thanks again,

Mike

Mike ... Sounds like the screws aren't original.  Don't try to go by the color code anymore.  It assumes they are in the right place, and you know where that is going to lead you.  (Although, if it is reversed, it would be charging the trailer frame.  The a/c unit could be a source of your leakage.

Check and measure.

Good advice.  Now here's a thought (I'll still do your tests as described earlier)...  I did some research and found that in a household outlet, the bigger slot on the left side is the neutral slot, the one on the right is the hot one.  The ground is, of course, centered below the two.

If you notice, the green ground screw is at the top of the inlet.  Let's picture the wiring as it leaves the outlet from the barn/generator.  Big slot on left side, littler one on right, ground below.  Now when the extension cord reaches the inlet, we're reversed 180 degrees on the outside of the trailer (ground is top, so neutral slot is on right side and hot is on left side).  Well, if we wire things the "traditional way" inside the trailer to the inside electrical outlet, with this 180 degree rotation at the inlet outside the trailer, then my black wire in the picture is actually electrically neutral.  The yellow wire is hot.  SO... the trailer is most likely reverse-wired.

Again, I'll doublecheck with your test, but I think I've figured this one out.

A couple of grounding questions.  The green wire appears to run up to the A/C...  I don't know how A/C systems are installed, but do they typically have ground/hot/neutral wires?  Short of removing the ceiling, I want to take an educated guess as to where this green wire ends up.  I assume it is NOT screwed into the trailer frame somewhere else, but runs to the A/C.

Also... how can I connect the inlet ground to the frame, short of running a wire out of the box and connecting it to a hole I drill in the frame?  I'll look for other options within the box's mounting hardware... maybe that will reveal some options short of this...  Seems odd that Silver Star would leave this wire unconnected from the factory...

Thank you,

Mike

Mike ... The a/c unit will have ground/hot/neutral wires.   

For grounding: The best practice is to take a wire to a hole drilled into the frame.  Grind the paint off and dab a bit of anti-oxidant between the bare metal connectors. Steel rusts and aluminum oxidizes.. This is a safety point so you don't want it to fail.  AND you won't know it's failed until you need it.

Look at all the posts on this forum about trailer running lights, brakes, turn signals, etc.  Most are problems based on a poor electrical ground.  These are only the 12 volt connectio.  You might reconsider the quality of the ground connection your life is depending on instead of a short cut.

Very true!!!  Who knows what would have happened!?!?  I don't get how such a connection could have been overlooked.

I rewired things as I said I would and did some tests.  Everything is ops normal now.  No more voltage leaking through the trailer frame to the ground.  Much better.

This weekend, I am going to buy NEW wiring and a new inlet and re-do this entire circuit with wiring I believe is trustworthy.  Not happy with the workmanship the trailer came with.

I suppose my best option is to run a wire out of the box, drill a small hole in the frame, and use that as my main ground attachment for now.  I'm not familiar with the grounding bus or how to install one.  I assume this would be done by connecting a grounding strap to the frame from the box, then connecting all other grounds internally to the box (the bus would be tied to the frame via the grounding strap.)  I'll see if I can find a grounding box at Lowe's.

Thank you ALL...  Feel much safer now... glad I'm not without my horses or MY WIFE who just happens to be 3 months pregnant with our 2nd child!!